化学工程与工艺专业本科毕业论文外文翻译.doc

外文翻译分子印迹溶胶凝胶材料在线固相萃取高效液相色谱联用测定水样中痕量五氯苯酚韩德满 方国珍 严秀平摘 要：通过合并表面分子印迹技术和溶胶凝胶相结合的方法制备高选择性分子印迹氨基功能化硅球，并应用该材料在线固相萃取高效液相色谱联用测定水样中痕量五氯苯酚。通过傅立叶红外光谱,扫描电镜，氮吸附和静态吸附实验对PCP印迹硅球进行表征。分子印迹功能化硅球具有高选择性，吸附、解吸动力学速度快的特征。在上样流速为5 mL min-1,预富集2 min条件下,富集倍数为670,检测险为(S/N=3)6 ng L-1。对10 mg L1的五氯苯酚在线固相萃取9次的精密度为3.8 %。在线固相萃取痕量五氯苯酚的线性系数为0.9997。此方法被用于当地湖水,河水,废水中五氯苯酚的测定。 关键词：五氯苯酚；在线固态萃取法；分子标记法；高效液相1.引言五氯苯酚（Pentachlorophenol, PCP）是持久性有机污染物之一，在农业上被作为一种常用的杀虫剂以及在木材防腐剂中作为消灭白蚁的杀虫剂被广泛应用1，由于它的毒性以及累积性,已被美国环境保护局列为优先控制污染物之一2。PCP比较稳定，在动植物体内的富集率高，能抑止生物代谢过程中氧化磷酸化作用，可导致动物肺、肝、肾脏以及神经系统的损伤。PCP除了作为木材防腐剂、农药等进入环境中外，还直接通过工业排放进入水环境中，以及通过饮用水和纸浆漂白废水中天然或合成化合物的氯代反应间接合成，以及苯氧烷酸和六氯苯等农药的降解生成。PCP的广泛使用已经造成世界范围的土壤和地下水污染问题。因此，去除和测定环境及生物样品中PCP具有重要的现实意义。分子印迹技术是当前发展高选择性材料的主要方法之一3，4。最近分子印迹溶胶-凝胶材料被广泛地研究58,这种材料是通过常规的溶胶-凝胶过程,把模板分子引入到刚性的无机,无机-有机网络中, 除去模板分子后在聚合物的网络结构中留下了与模板分子大小和形状相匹配的立体空穴，同时空穴中含有识别模板分子的结合位点，对模板客体分子表现高度的选择识别性能。这些材料往往对模板分子具有高的亲和性和选择性,但印迹点的暴露却不够充分。由于模板分子与功能位点被埋在聚合物介质中,传质速度慢,所以吸附-脱附动力学不理想。表面分子印迹技术是解决这一问题的有效方法之一9。将印迹点固定在表面的材料具有高选择性,印迹点接触容易,传质速度和结合动力学快等优点10，11。本文报道了一种结合位点在表面的分子印迹氨基功能化硅球新材料,用于选择性去除和分离五氯苯酚。该材料用表面分子印迹与溶胶-凝胶技术相结合的方法进行制备。并详细描述和讨论了该材料的表征以及流动注射在线选择性固相萃取与高效液相色谱联用测定环境样品中的五氯苯酚。2.实验部分2.1 仪器和试剂DU-8B紫外可见分光光度计（Backman Co. USA）；Waters 600E高效液相色谱仪和Waters 2996 二极管阵列检测器（Milford, MA, USA）；Symmetry-C18反相色谱柱(5 m, 4.6 mm i.d. 25 cm, Waters, USA)；傅立叶红外光度计（4000400 cm-1）（Nicolet, USA）；FIA-3100型流动注射仪(北京万拓仪器有限公司)；Hitachi S-4100型场发射扫描电镜(Japan);CHEMBET-3000吸附计(Quantachrome,USA)。四乙氧基硅烷和3-氨基丙基三乙氧基硅烷购于武汉大学化工厂；五氯苯酚（PCP）、2,4-二氯苯酚（2，4DCP）、苯酚（Ph）和甲烷磺酸购于天津化学试剂有限公司；硅球（80-120目，青岛海洋化工有限公司）作为吸附支持体；流动相甲醇购自康科德试剂公司(天津), 所用试剂为分析纯，水为二次去离子水（DDW）。2.2 五氯苯酚分子印迹、非印迹聚合物的制备2.2.1 硅球的活化8 g硅球（80120目）置于250 mL三颈瓶中，加入60 mL 33%甲烷磺酸水溶液，电磁搅拌下回流反应8 h。滤出固体，用蒸馏水反复冲洗至水溶液为中性，于70 真空干燥8 h。 2.2.2 PCP印迹硅球的制备 在100 mL 带塞的锥形瓶中加入5 mL乙醇，1 g PCP，2 mL 3-氨基丙基三乙氧基硅烷，搅拌，反应20 min；加入1 g活化硅球，搅拌5 min，加入2 mL四乙氧基硅烷，搅拌10 min，再加入1 mL 1mol L-1醋酸，在室温下孵化10 h，过滤，用乙醇洗涤，置真空干燥箱中于100 下老化10 h。 将上述制备好的PCP硅球放在100 mL的带塞锥形瓶中，加入25 mL乙醇和25 mL 1 mol L-1盐酸，磁力搅拌2 h, 过滤，用乙醇、水洗涤，再用0.1 mol L-1 氢氧化钠、水洗涤，在80 下干燥12 h。模板印迹过程Fig.1所示.制备非分子印迹硅球除不加模板分子PCP外，其余操作步骤同上述分子印迹硅球的制备。Figure. 1 Protocol for template imprinting of PCP.2. 3 吸附实验2.3.1 吸附动力学实验 准确称取50 mg PCP分子印迹硅球于10 mL的容量瓶中, 用200 mg L-1的PCP乙醇溶液定容到刻度，在室温下振荡不同的时间，离心分离，在紫外-可见光度计上测定上清液中PCP的浓度，测定波长为215 nm。2.3.2 分子印迹硅球对PCP的平衡结合实验 准确称取50 mg 分子印迹硅球于10 mL的容量瓶中，分别加入不同浓度的PCP乙醇溶液，振荡1 h，离心分离，在紫外-可见光度计上测定上清液中PCP的浓度，测定波长为215 nm。同时平行做非分子印迹硅球对PCP平衡结合实验。2.3.3 竞争吸附实验选择苯酚、2,4-二氯苯酚作为竞争物，考察所合成的材料对五氯苯酚的选择性。分别准确称取多份20 mg 印迹、非印迹材料于10 mL的容量瓶中，分别加入含200 mg L-1苯酚、2,4-二氯苯酚和PCP的甲醇混合溶液至刻度，振荡1 h，离心分离，在高效液相色谱仪上测定上清液中苯酚、2,4-二氯苯酚和PCP的浓度。2.3.4 用印迹吸附材料在线选择性固相萃取高效液相色谱联用测定五氯苯酚的程序为了评价PCP分子印迹材料对PCP在线选择性固相萃取能力，采用在线微柱预富集分离与高效液相色谱联用技术。50 mg的PCP分子印迹材料装在1.5 cm 4 mm i.d.的不锈钢小柱中，此不锈钢小柱代替高效液相色谱仪六通阀中的进样环。采用甲醇-乙酸（99.7 + 0.3（v/v）作高效液相色谱流动相。在线微柱预富集与高效液相色谱联用装置如Fig.2, 第一步，样品溶液或标准溶液通过流动注射泵以5 mL min-1速度通过装有PCP分子印迹材料的预富集微柱2 min, 使溶液中的PCP富集在微柱上，流出物流入废液池，高效液相色谱仪的六通阀位处于负载位（Fig.2a）；第二步，吸附在预富集柱上的分析物通过高效液相色谱的流动相以1 mL min-1的流速反冲洗脱进入高效液相色谱仪的分离分析柱，高效液相色谱仪的六通阀位由负载位转到注射位（Fig.2b），分析物在分析柱上被分离，通过紫外检测器检测记录。Fig. 2 Flow diagram of the on-line solid phase extraction preconcentration coupled with HPLC. HPLC injector valve position: (a) load; (b) inject.2.4 结果与讨论2.4.1 傅立叶红外光谱,扫描电镜和氮吸附的特征 为了证实-NH键合到活化硅球上，对活化硅球、五氯苯酚印迹和非印迹硅球进行了红外表征,结果见Figure.3。在1100 和 976 cm-1的吸收分别表示Si-O-Si和Si-O-H的伸缩振动。在3442 cm-1 和 1636 cm-1的吸收表示OH的振动。围绕780 和 470 cm-1的波段表明了Si-O振动。与未被修饰的活化硅球相比，最大区别在于印迹硅球和非印迹硅球在1560 cm-1左右有N-H伸缩振动吸收，在2935 cm-1有脂肪链C-H伸缩吸收，表明修饰后-NH键合到活化硅球表面上。印迹和非印迹功能化吸附硅球有相似的红外光谱图(Fig.3)。 Fig .3 FT-IR spectra of the activated silica gel, PCP-imprinted and nonimprited sorbent扫描电镜图(Fig.4)表明印迹材料的表面比活化硅球的表面要粗糙且具有多孔的结构,这表明在硅球表面已键合上了一层印迹物。 Fig. 4 SEM image of the surface of (a) the PCP-imprinted sorbent ; (b) the activated silica gel.氮吸附的结果为:印迹材料的比表面为177 m2g-1,平均孔径为8.8 nm;活化硅球的比表面为355 m2g-1,平均孔径为8.6 nm。2.4.2 印迹材料对PCP的吸附动力学10 mL 200 mg L-1的PCP乙醇溶液在50 mg分子印迹材料上的吸附动力学实验结果表明：吸附5 min之后相对吸附容量可以达到71.8%, 60 min之后吸附基本达到平衡。2.4.3 吸附材料对PCP的平衡结合实验为了评价所合成的材料对模板分子PCP的结合能力，以平衡吸附实验测定了在室温下吸附材料对模板分子的吸附容量。吸附等温线(Fig.5), 由图可知，印迹材料的吸附容量可达到93 mg g-1，在相同条件下，印迹材料对模板分子的吸附容量明显高于非印迹材料对模板分子的吸附容量，可能是由于在印迹材料的制备过程中，模板PCP的存在使功能基进行了有序的排列，形成了一定的立体化学结构，当模板分子被洗脱除去以后，留下了特制的空穴，这种空穴对模板分子具有高的识别性。而在非印迹材料中，由于与官能团-NH2相连的-CH2-CH2-CH2-的灵活性，使配体的方向容易发生变化，从而使几何构型有一个很大的变化范围，配体和模板分子的配位不确定，导致了材料对模板分子的吸附容量低。Fig.5 Loading isotherm of PCP onto imprinted and nonimprinted sorbents2.4.4 印迹材料对模板分子PCP的选择性为了考察印迹材料对模板分子PCP的选择性，选择性质、结构类似物苯酚(Ph)、2,4-二氯苯酚(2,4-DCP)作竞争物。测定10 mL 200 mg L-1 PCP、2,4-DCP和Phenol三种物质混合物在20 mg印迹、非印迹材料上的吸附百分率、负载容量、分配系数、对PCP的选择性系数k和相对选择性系数k，结果见Table 1。Table 1 Competitive Loading of PCP, 2,4-DCP and Phenol (Ph) by the Imprinted and Nonimprinted SorbentsSorbent Initial solution (mg L-1)Capacity (mg g-1)K d (mL g-1)kk PCP2,4-DCPPhPCP2,4-DCPPhPCP 2,4-DCPPhPCP/2,4-DCPPCP/PhPCP/2,4-DCPPCP/PhImprinted 20020020080.44.4 2.02051 231089.2205.110.017.8Nonimprined20020020046.69.07.043649388.911.5Note: Kd, distribution coefficient, Kd =(Ci Cf) / Cf volume of solution mL / mass of gel g, where Ci and Cf represent the initial and final concentrations, respectively; k, selectivity coefficient, k = Kd1/Kd2; k, relative selectivity coefficient, k = kimprinted/knonimprinted.实验结果表明：印迹材料对PCP的吸附百分率、负载容量分别是80.4%和80.4 mg g-1明显高于非印迹材料对PCP的吸附百分率（46.6% ）、负载容量（46.6 mg g-1 ），而印迹材料对2,4-DCP和Ph的负载容量分别是4.4 mg g-1 和2.0 mg g-1，明显低于非印迹材料对2,4-DCP和Ph的负载容量（分别是9.0 mg g-1 ，7.0 mg g-1）；印迹材料和非印迹材料对PCP和2,4-DCP的相对选择性系数为10.0；对PCP和Ph的相对选择性系数为17.8。这一方面体现了印迹材料对PCP的印迹效果,另一方面是由于PCP(pKa = 4.93)的酸性比2,4-DCP(pKa = 7.85)强, 所以 PCP 和NH2之间的作用力也比 2,4-DCP(Ph)大。2.4.5 在线选择性固相萃取高效液相色谱联用测定PCP对固相萃取高效液相色谱联用测定PCP的各种影响因素如样品pH值,上样时间,上样速度，洗脱剂和脱附时间等进行了优化。在上样流速为5 mL min-1,预富集2 min条件下,对不同酸度条件下分子印迹材料对10 mg L1的五氯苯酚吸附效果进行了试验,实验结果表明最佳pH值范围为6.87.6,在此范围之外所测得的PCP峰面积相应减少, 酸度太强会使印迹材料质子化,碱度太强五氯苯酚以阴离子的形式存在,这都不利于五氯苯酚在印迹材料上的吸附。采用与上述浓度相同的PCP溶液在6 mL min-1的流速固定下，考察上样时间对PCP在印迹材料上吸附的影响，结果表明在12 min内色谱峰面积随时间增大线性增加；固定上样时间2 min，考察上样速度对PCP在印迹材料上吸附的影响，色谱峰面积随流速增大到5.5而呈线性增加。这些结果表明PCP在印迹材料上的吸附动力学很快,可以通过提高上样速度和延长上样时间来提高富集倍数。为简单起见,采用优化的流动相(methanol, HAc and water=90:0.3:9.7)作洗脱剂并对脱附时间进行试验,在00.3 min内PCP色谱峰面积急剧增加,在0.51.0 min内增加缓慢(约6%),在1.010 min内趋于平缓.因而选择2 min作为脱附时间以确保PCP完全洗脱。为了考察印迹材料对模板分子PCP的在线预富集选择性，选择含量分别为10 mg L1的五氯苯酚、苯酚、2,4-二氯苯酚的混合标准物质通过预富集柱来试验,结果见Fig.6. 通过流动相洗脱后, 只有 PCP在色谱图上明显出现。表明 PCP能被印迹材料选择性吸附而苯酚、2,4-二氯苯酚基本上不被吸附。Fig .6 Chromatograms of (a) direct injection of 20 mL standard mixture solution containing 10 mg L-1 of phenol , 2,4-DCP and PCP each; (b) 10 mL standard mixture solution of 10 mg L-1 of phenol, 2,4-DCP and PCP with on-line solid phase extraction preconcentration;2.4.6分析特征量PCP分子印迹材料对PCP具有很好的选择性，能在线选择性地固相萃取水溶液中痕量PCP，作为微柱填充材料与高效液相色谱联用可实现痕量PCP的在线富集和检测。在上样流速为5 mL min-1,预富集2 min条件下,富集倍数为670,检测险为(S/N=3)6 ng L-1。对10 mg L1的五氯苯酚在线固相萃取9次的精密度为3.8 %。在线固相萃取痕量五氯苯酚的线性系数为0.9997(Table 2)。此方法被用于当地湖水,河水,废水中五氯苯酚的测定.回收率在9193 %之间(Table 3)。Table 2 Figures of Merit for the On-line Solid Phase Extraction Coupled with HPLC for Determination of Trace PCPenrichment factors a670detection limit (S/N=3) (ng L-1)6peak area precisionb (n = 9) (%, RSD)3.8linear range of the calibration graph (mg L-1)0.05-500sample consumption (mL)10a compared with direct injection of 20 mL sample solution b for 0.2 mg L-1 PCPTable 3 Analytical Results for the Determination of PCP in Real Water Samplessampleconcentration determined(mean s, n = 3)/mg L-1recovery of 2 mg L-1 PCP spiking/%wastewater0.16 0.0291 3lake water0.09 0.0193 2river water0.08 0.0192 12.5 结论用表面分子印迹与溶胶凝胶相结合的技术合成了对五氯苯酚具有高选择性的印迹氨基功能化硅球。所合成的材料具有高亲和性，高选择性，较高的吸附容量，印迹位点容易与目标物接近等优点。对从水溶液中选择性去除和分离五氯苯酚具有很好的应用前景。作为微柱填充材料与高效液相色谱联用可实现痕量PCP的在线富集和检测。参考文献：1 T.B. Gaines, Toxicol. Appl. Pharmacol. 14 (1969) 515.2 G.W. Muna, N. Tasheva, G.M. Swain, Environ. Sci. Technol. 38 (2004) 3674.3 M. Li, S.F. Tsai, S.M. Rosen, R.S. Wu, K.B. Reddy, J.D. Cesare, S.J. Salamone, J. Agric. Food Chem. 49 (2001) 1287.4 Toxic Substance Control Act, U.S. Environmental Protection Agency, Washington, DC, 1979.5 A. Martin-Esteban, Fresenius J. Anal. Chem. 370 (2001) 795.6 L.I. Andersson, Bioseparation 10 (2001) 353.7 F.L. Dickert, O. Hayden, Anal. Chem. 74 (2002) 1302.8 S. Dai, M.C. Burleigh, Y.H. Ju, H.J. Gao, J.S. Lin, S.J. Pennycook, C.E. Barnes, Z.L. Xue, J. Am. Chem. Soc. 122 (2000) 992.9 A. Katz, M.E. Davis, Nature 403 (2000) 286.10 M.K.-P. Leung, C.-F. Chow, M.H.-W. Lam, J. Mater. Chem. 11 (2001) 2985.11 S. Dai, M.C. Burleigh, Y. Shin, C.C. Morrow, C.E. Barnes, Z. Xue, Angew. Chem. Int. Ed. Engl. 38 (1999) 1235.12 H.-H. Yang, S.-Q. Zhang, F. Tan, Z.-X. Zhuang, X.-R. Wang, J. Am.Chem. Soc. 127 (2005) 1378.13 G.-Z. Fang, J. Tan, X.-P. Yan, Anal. Chem. 77 (2005) 1734.14 N. Masque, R.M. Marce, F. Borrull, J. Chromatogr. A 793 (1998) 257.外文文献 ournal of chromatography A 2005(1100)Preparation and evaluation of a molecularly imprinted solgel materialfor on-line solid-phase extraction coupled with high performanceliquid chromatography for the determination of tracepentachlorophenol in water samplesDe-Man Han Guo-Zhen Fang Xiu-Ping Yan Abstract：A highly selective imprinted amino-functionalized silica gel sorbent was prepared by combining a surface molecular imprinting technique witha solgel process for on-line solid-phase extractionHPLC determination of trace pentachlorophenol (PCP) in water samples. The PCP-imprintedamino-functionalized silica sorbent was characterized by FT-IR, SEM, nitrogen adsorption and the static adsorption experiments. The imprinted functionalized silica gel sorbent exhibited high selectivity and offered a fast kinetics for the adsorption and desorption of PCP. The prepared sorbent was shown to be promising for on-line solid-phase extraction for HPLC determination of trace levels of PCP in environmental samples. With a sample loading flow rate of 5ml min1 for 2 min, an enhancement factor of 670 and a detection limit (S/N = 3) of 6 ng l1 were achieved at a sample throughput of five samples h1. The precision (RSD) for nine replicate on-line sorbent extractions of 10g l1 PCP was 3.8 %. The sorbent also offered good linearity (r = 0.9997) for on-line solid-phase extraction of trace levels of PCP. The method was applied to the determination of PCP in local lake water, river water and wastewater samples.Keywords: Pentachlorophenol; Solid-phase extraction; Molecular imprinting; High performance liquid chromatography1. IntroductionPentachlorophenol (PCP) is used as a general herbicide in agriculture and as an insecticide for termite control in the preservation of wood 13. Because of its toxicity and unpleasant organoleptic properties (concentrations as low as a fewg/l of phenol affect the taste and odour of water and fish), PCP has been included in the list of priority pollutants by the US Environmental Protection Agency (EPA) 4. Consequently, the development of new sorbents for selective removal and separationof pentachlorophenol in environmental matrices is of particular significance.Molecular imprinting is an attractive method for the preparation of selective sorbents 5,6. Recently, molecularly imprinted solgel materials (MISGMs) have been extensively studied 710. MISGMs are fabricated by a conventional solgel process and incorporation of the template molecules into rigidinorganic or inorganicorganic networks. After removal of the template, molecular cavities with distinct pore size, shape or chemical functionality remain in the cross-linked host. These “molecularly designed cavities” showan affinity for the template molecule over other structurally related compounds. However,most of these materials exhibit high affinity and selectivity but poor site accessibility to the target molecules. So, the kinetics of the sorption/desorption process is unfavorable, as the template and functionality are totally embedded in the polymer matrices and the mass transfer is slow. A promising solution to this problem is the development of surface molecular imprinting 11.The materials with binding sites situated at the surface show many advantages including high selectivity, more accessible sites, fast mass transfer and binding kinetics 12,13. The purpose of this work is to prepare a new molecularly imprinted amino-functionalized silica gel sorbent with binding sites situated at the surface with respect to PCP by a surface imprinting technique in combination with a solgel process, and to apply it to on-line selective solid-phase extraction (SPE) coupled with HPLC for the determination of trace PCP in water samples.2. Experimental2.1. Materials and chemicalsSilica gel (80120 mesh, Qingdao Ocean Chemical Co., Qingdao, China) was used as the support to prepare the PCPimprinted functionalized sorbent. Tetraethoxysilicane (TEOS),3-aminopropyltriethoxysilane (APTES) (Wuhan University Chemical Factory, Wuhan, China), pentachlorophenol (PCP), phenol (Phe), 2,4-dichlorophenol (2,4-DCP), acetic acid (HAc)(Tianjin Chemical Co., Tianjin, China) were used in this study. Doubly deionized water (DDW, 18Mcm1) obtained from a WaterPro water system (Labconco Corporation, Kansas City, MO, USA) was used throughout the experiments. The mobile phase used for HPLC experiments was a mixture of methanol (Concord Technology Co. Ltd., Tianjin, China), HAc and water (90:0.3:9.7), andwas filtered through 0.45-m filter prior to use. All reagents used were of at least analytical grade.2.2. SamplesWater samples were collected from local lake, river and wastewater of timber factory. The glass bottles for sample storage were thoroughly washed with detergents, water, methanol and doubly deionized water, and dried before use. The samples were filtered through 0.45-m Supor filters, stored in precleaned glass bottles. Water samples were adjusted to pH 7.07.6 with HCl or NaOH to insure the efficient solid-phase extraction of the analytes by the sorbent, and analyzed immediately.2.3. InstrumentationThe chromatographic system consisted of a Model 600 HPLC pump and a Waters 2996 photodiode array detector (Waters, Milford, MA, USA). All separations were achieved on an analytical reversed-phase column (Symmetry-C18 5m, 4.6mm i.d.25 cm long, Waters, USA) at a mobile flow rate of 1.0 ml min1 under isocratic conditions at room temperature. The Empower software was used to acquire and process spectral and chromatographic data. The photodiode array detector was operated between 210 and 400 nm.A Model FIA-3100 flow injection system (Vital Instruments, Beijing, China) was used for solid-phase extraction preconcentration. Tygon pump tubes were used for delivering the sample solution. Small-bore (0.5mm i.d.) PTFE tubings were adapted for all connections, which were kept the shortest possipossible length to minimize the dead volume. The SEM micrographs of the sorbents were obtained at 20.0 kV on a Hitachi S-4100 field emission scanning electron microscopy. FT-IR spectra (4000400 cm1) in KBr were recorded using a Magna-560 spectrometer (Nicolet, USA).Average pore diameter and surface area of the sorbents were measured by nitrogen adsorption with a Model CHEMBET-3000 Sorptometer (Quantachrome, USA).2.4. Procedures for the preparation of the PCP-imprinted amino-functionalized silica gel sorbentTo activate the silica gel surfaces, 8 g of silica gel (80120 mesh) was mixed with 60 ml of 33% methanesulfonic acid and refluxed under stirring for 8 h. The solid product was recovered by filtration, washed with DDW to neutral and dried under vacuum at 70 for 8 h. To prepare the PCP-imprintedamino-functionalized silica gel sorbent, 1 g of PCP was dissolved in 5ml of ethanol, and mixed with 2ml of APTES. The mixture was stirred for 20 min, then 4ml of TEOS was added. After stirring for 5 min, 1 g of activated silica gel and 1ml of 1mol l1 HAc (as catalyst) were added. The mixture began to co-hydrolyse and co-condense after stirring for a few minutes, then incubated for 10 h at room temperature. The product was filtrated and dried in a vacuum oven at 100 for 8 h. Thus, the activated silica gel surface was grafted with the complex. The sorbent was extracted with 25 ml of ethanol and 25 ml of 1 mol l1 HCl under stirring for 2 h to remove PCP (Fig. 1). The product was isolated by filtration, washed with ethanol + 6 mol l1 HCl (1:1), neutralized with 0.1 mol l1 NaOH, and washed with pure water. Finally, the sorbent was dried under vacuum at 80 C for 12 h. For comparison, the nonimprinted functionalized silica gel sorbent was also prepared using an identical procedure, but without the addition of PCP.2.5. Static adsorption testTo measure adsorption capacity, 50 mg of PCP-imprinted or nonimprinted sorbents was equilibrated with 10 ml of various concentrations of PCP dissolved in ethanol. The mixtures were mechanically shaken for 1 h at room temperature and separated centrifugally. The supernatants were measured for the unextracted PCP by UV spectrometry. Adsorption and competitive recognition studies were performed with PCP and structurally related compounds, phenol and 2,4-DCP at the 100 mg l1 level. Uptake kinetics of PCP by the imprinted functionalized silica gel sorbent was also examined. Fifty milligrams of the sorbent was added to 10 ml of 100 mg l1 of PCP ethanol solution. The mixture was mechanically shaken for 5, 10, 30, 60, 90 and 120 min at room temperature, respectively, then separated centrifugally. The supernatants were measured for the unextracted PCP by UV spectrometry.Fig. 1. Protocol for template imprinting of PCP.2.6. Procedures for selective on-line SPEHPLCdetermination of PCP using the imprinted sorbentTo evaluate the applicability of the imprinted functionalizedsilica gel sorbent for on-line SPEHPLC determination of trac